Dr. Paul Doty
Dept. Chemistry
Harvard University
Cambridge, Mass.

Dear Dr. Doty:

While optlinang a review on bacterial recombination mechaniams, I have
been struck by the paucity of phyeical measurem nts on pnemmoconcal dna, at
least mMeaguremnts I could give published citations for. The 1943 Avery et
al. paper mentioned some preliminary studies, which have been requoted but
never given in any detail: I would be especially anxious for an account
which emphasized the difficulties in dealing with linear polyeleoctolytes
like DNA. I Amagthne that such studies are now in progress, but am I wrk
right in the statement that most of the assertions of particle size of the
transfoming agent are based on analogy with other material?

In particular, I would be grateful to you for any recent references
(say since 1954) that would be immediately relevant to the dimensions and
homogeneity of preparations used in the transfar mation experigents. As your

own work on this reaches print, I would alse be grateful to you for reprints
of it.

Xm I am rather anxious to aygold compounding the confusion and not refer
to conclusioms that can't be documented, But it would be personally helpful

for my own state of mind if you can mote more recent work that has not yet
published.

With best regards

Yours sincerely,

Joshua Lederberg
Professor of Genetics